This invention relates to insulated trailer doors such as doors to refrigeration vehicles. In particular the invention is concerned with fastening of hardware to such doors.
By the term hardware the applicant means hinges, door latches, locks and the like. A refrigeration door of the kind with which this invention is concerned and to which the hardware is attached is conventionally constructed by spaced walls between which there is an insulation material such as foamed polyurethane. This material is conventionally formed in situ between the walls. In the foaming process a skin of high density foam forms on the outside of the foam and adjacent the inside of the walls, and this skin effectively acts as a good sealant against the ingress of moisture and thereby prevents any deterioration in the insulating qualities of the foam. Puncturing of the foam and the seal for any reason would consequently cause a deterioration in insulation properties.
The current practice of affixing hardware to the refrigeration door requires the fastening element to be affixed to the outside wall of the door with the nut or head of a bolt fastening device disposed in the body of the foam. Initially when the foam is formed the seal forms around the fastening device and effective insulation is obtained. However, it has been found that in use when a trailer is backed into a loading dock or the like the hardware and fastening devices which are upstanding of the door face are urged inwardly into the foam when the trailer rear abuts the dock. With time, the hardware and fastening devices require replacement and it is then necessary to cut through the foam to extract the fastening devices.
Also in the known art it is conventional to provide a reinforcing or stiffener plate between the walls and in contact with the fastening device so as to insure effective anchorage of the fastening device to the walls. The effect of the stiffening devices is that zones are formed within the cavity in which foaming takes place and as a consequence voids develop during foaming. Less effective insulation is a result.
The walls may be of metal, plywood or of a suitable synthetic plastic material.
As an illustration of the prior art having these disadvantages reference can be had to U.S. Pat. No. 3,003,810.
It is an object of the present invention to provide a mounting for hardware on an insulation door, which, it is believed minimizes the problems and disadvantages currently experienced. According to the invention the means for mounting hardware on such an insulation door includes a support rigidly mounted to the outside wall of the door and openings in the support for accommodating fastening elements which elements fixedly mount the hardware to the support. The support can be constituted by U-shaped cross beams which extend transversely across the trailer door so that a rectangular cavity is formed between the wall of the door and the cross beam element. Openings in the cavity house the head or nut of a fastening element and the remote end of the fastening element passes through a mating aperture in the hardware such that as the fastening element is tightened effective fastening of the hardware to the support is achieved.
Other and more detailed objects and advantages will appear below.